def find(words):
    """

    find the longest common prefix of all string in words

    :type words : list(str)
    :rtype str
    """

    wc = len(words);
    if wc == 0:
        print('At least 1 string, please!');
        return None;
    elif wc == 1:
        return words[0];

    for i in range(0, len(words[0])):
        letter = words[0][i];
        for j in range(1, wc):
            jword = words[j];
            if i >= len(jword) or letter != jword[i]:
                if i == 0:
                    return '<* No common prefix *>';
                return words[0][:i];
    return words[0];
